music room in basement sound insulation

[Thorfun]

greetings all. as a kind-of follow on from 

I wanted to start a new discussion on my sound insulating needs for the music room in more detail as I'm concerned I'm overthinking and over-(sound)engineering things as usual.

 

this is the music room. I'm planning on splitting is as shown in to 2 separate rooms, one with the recording desk and the other for the instruments.

 

 

the room is in the basement and the hashed walls are blocks laid-flat, so 225mm thick and the outside walls are 250mm reinforced concrete with the earth outside. I was planning on using this system from the Whitebook but with a second skin of standard 12.5mm board for the pre-existing walls (I need to use standard board as I can't fit 1200x2400 boards down the stairs to the basement so need a board that comes in 900x1800mm) but I'm wondering if that's complete overkill! I'm doubting that the Rockwool insulation with have much of an effect when there's 225mm concrete blocks behind it as that mass will stop a lot of the noise. and for the outside walls with the earth behind what's the point of even doing a second skin of plasterboard!? so I'm leaning towards scrapping the idea of the 25mm layer of insulation and the second skin, what do you think?

 

I'm thinking that my focus for sound insulation needs to be on the new partition wall, the door ways and the ceiling as the kitchen is above this room. so for the ceiling I am planning on using this system and putting 100mm RWA45 above it and also putting a layer of MLV between the 2 layers of standard 12.5mm plasterboard.

 

for the partition wall I was thinking of using this system and also putting MLV between the 2 layers on the music room side of the wall.

 

for both the doorways I am planning 2 x FD30 doors with MLV on one face and sealed around the edges with rubber.

 

I would appreciate anyone's input on this. tbh, I think I'm happy with the partition wall and ceiling plan but I want someone to tell me honestly that anything more than a single skin of 12.5mm plasterboard against the existing block and concrete walls is a waste! and how, if at all, would you do it differently.

 

for context, our drummer is really <expletive deleted> loud so the amps have to be cranked up to be heard over him. previously as rehearsals we hit around 106dB looking at my Apple health data.

[Iceverge]

As usual with sound you have 4 issues. 

 

1. Airpathways. The big issue here is the doors. They're very lightly to be the weak point. Really focus on getting an absolutely seal all around them. (This may require dedicated ventilation to the music room)

 

Similarly seal the ceiling plasterboard and the stud partition plasterboard with acoustic sealant in a hermitic fashion. 

 

2. Decoupling. Mainly an issue with the stud walls and ceiling. A dropped metal ceiling or resilient bars will do here. 

 

3. Reverberation. "The drum effect". Anything that you hit a thump of your fist that noticeably acts in this manner needs a layer of fluffy stuff inside to prevent it. Similarly dissuading harmonic frequencies is important. Use differing thickness of plasterboard on both sides of a wall for example. Add some foam to the back of the fire doors to stop sound bouncing around in the void there. 

 

As it's a dedicated music room you could consider lining the walls and ceiling with acoustic foam too. 

 

4. ADD MASS. Not required for the 225mm wall or the poured concete wall. There's literally tonnes there already. Remember all that you are doing is buying kilogrammes, not magic beans. 

 

Dense rockwool, MLV and other secret sauces are expensive ways to buy these kgs. 

 

Standard plasterboard, soundbloc and OSB and are all the cheapest at about 60p per kg from memory. 

 

More is better, including on the doors. 

 

 

 

 

Edited November 4 by Iceverge

[Thorfun]

9 hours ago, Iceverge said:

1. Airpathways. The big issue here is the doors. They're very lightly to be the weak point. Really focus on getting an absolutely seal all around them. (This may require dedicated ventilation to the music room)

 

Similarly seal the ceiling plasterboard and the stud partition plasterboard with acoustic sealant in a hermitic fashion. 

yeah. I agree with this. I'm actually thinking about hanging the door opposite directions as well so that the hinges/latches are at different ends. the music room and control room area already has MVHR in each part as I always thought about doing this splitting of it. and acoustic sealant was definitely going to be used everywhere!

 

9 hours ago, Iceverge said:

2. Decoupling. Mainly an issue with the stud walls and ceiling. A dropped metal ceiling or resilient bars will do here. 

 

yep. dropped metal ceiling in the plan. 🙂 

 

9 hours ago, Iceverge said:

3. Reverberation. "The drum effect". Anything that you hit a thump of your fist that noticeably acts in this manner needs a layer of fluffy stuff inside to prevent it. Similarly dissuading harmonic frequencies is important. Use differing thickness of plasterboard on both sides of a wall for example. Add some foam to the back of the fire doors to stop sound bouncing around in the void there. 

 

As it's a dedicated music room you could consider lining the walls and ceiling with acoustic foam too. 

ok, so this makes sense and having the 25mm of fluffy stuff (not necessarily RWA45 though) behind the plasterboard of the perimeter walls will help with this but be negligible for the total mass of the wall.

 

I have been looking at acoustic foam but wasn't sure I wanted the entire room covered in it but I'll research it some more.

 

9 hours ago, Iceverge said:

4. ADD MASS. Not required for the 225mm wall or the poured concete wall. There's literally tonnes there already. Remember all that you are doing is buying kilogrammes, not magic beans. 

 

Dense rockwool, MLV and other secret sauces are expensive ways to buy these kgs. 

 

Standard plasterboard, soundbloc and OSB and are all the cheapest at about 60p per kg from memory. 

so I think you're saying that on the perimeter walls where I have the concrete and blocks a single skin of 12.5mm plasterboard will suffice as those walls already have a lot of mass. so my concern is the partition wall and ceiling (as I thought!). I can't use soundbloc as that only comes in 1200x2400 sheets unless I'm willing to cut it in half and then carry it down to the basement. but I did find Gyproc Plank which has a density of 14.7kg/m2 (denser than Soundbloc F) and comes in sheets of 600x2400. so I'm now thinking a layer of that with a standard 12.5mm plasterboard on that should give a mass of around 22.7kg/m2. I know MLV is expensive but if I add a 2mm sheet of that which gives 5kg/m2 that will be a total of 27.7kg/m2 which is almost the same as 2 x 15mm Soundbloc F (28.2kg/m2). there is also the block and beam flooring above the metal ceiling which has a 50mm concrete screed on top of that so I think that should suffice!

 

9 hours ago, Iceverge said:

More is better, including on the doors. 

totally get this but it's knowing when to stop and fitting it all in our now non-existent budget.

[Onoff]

@Pocster

 

Sound proofing a basement?

 

Btw, how do you overcome cold bridging where the manacle rings are?

[saveasteading]

I don't think the above mention one thing. Avoid parallel faces, as this creates repeated reverberation.

 

The established principle  of egg boxes on the surfaces  still applies.

Don't overdo it or it becomes an anechoic chamber, which is equally unpleasant.  I stood 3m from a starter's gun, and heard only a single muted sound.

[Pocster]

4 hours ago, Onoff said:

@Pocster

 

Sound proofing a basement?

 

Btw, how do you overcome cold bridging where the manacle rings are?

I like "music room" aka sex dungeon and also "control room " presumably the cctv recording and editing suite?

 

Once chained the thoughts of "how do you overcome cold bridging " will become a distance memory as you experience the pleasures.....

[Alan Ambrose]

An old mate of mine designed radio & TV studios most of his working life. He said - 'there's no substitute for mass'. I'm thinking sand...

 

I might also check out the sound booths that wind instrument players can practice in.

 

 

[elite]

Pay particular attention to detailing on doors / windows, these will be your biggest problem. Is that a french door to the left of control room? It will probably be more leaky than others.

 

Consider making stud walls double & decoupled

 

Check your room ratios aren't going to cause acoustic issues

 

I suspect you'll want the room pretty "dead" at that sort of size, so incorporate absorbers / bass traps in the design early on

 

A great resource: https://johnlsayersarchive.com/

 

Keep us updated on your progress

[Thorfun]

10 minutes ago, elite said:

Is that a french door to the left of control room? It will probably be more leaky than others.

not a french door but a double width opening for double doors. but i'm not worried about that as i will have the new stud wall as a barrier between the live instruments and those doors.

 

18 minutes ago, elite said:

Consider making stud walls double & decoupled

 

i've thought about this and looking through the white book at their specific audio walls there's this option but it's 300mm thick which will eat in to the already small space of the control room.

 

[saveasteading]

Just thought...curtains...everywhere. then you can play around with the resonance. 

[Thorfun]

2 minutes ago, saveasteading said:

Just thought...curtains...everywhere. then you can play around with the resonance. 

it's an interesting idea but, tbh, i'm not too worried about how it sounds at the moment i just want to reduce the noise in the rest of the house. once i have that down to a dull-roar i can worry about treatments in each area to improve the sound quality. if that makes sense!

[elite]

As above, you need mass your best option is probably MLV PB sandwich

 

Is the space primarily for rehearsals or recording?

[saveasteading]

2 hours ago, Thorfun said:

i just want to reduce the noise in the rest of the house

Ok thats easy. It is all tried and tested.

Just remember that the contructions are tested in laboratories... a lump of wall inside a controlled testing box.

You will have junctions and corners, and services and doors.

 

I think i recall building a music room next to a maths classroom, and it worked out fine. I haven't got details any more but the requirements will be published.

Once you find the construction, which will be as dcsibed by others above, you should choose the next level up, to overcome the difference between laboratories and real life. And avoid service holes and doors.

 

Now it's  coming back to me. Stud walls with flexible (acoustic) bars and many layers of board, plus dense mineral wool. 

I think we sliced the floor slab under the wall to break continuity.

Floor above similar with plasterboard under a cushioned floor boards for density.

 

[Thorfun]

4 hours ago, elite said:

As above, you need mass your best option is probably MLV PB sandwich

 

Is the space primarily for rehearsals or recording?

Rehearsals/jamming

[Thorfun]

3 hours ago, saveasteading said:

Stud walls with flexible (acoustic) bars

I presume these are the same as resilient bars?

[saveasteading]

49 minutes ago, Thorfun said:

the same as resilient bars

Resilient is the right term, yes. 

[elite]

1 hour ago, Thorfun said:

Rehearsals/jamming

 

I was going to say I'd want the control room bigger if it was for recording. My knowledge is more on a recording build, but essentially bass will be your biggest issue, so lots of mass and decouple everything where possible. You will also want to kill reflections etc especially if you're loud, so soft furnishings will help a lot with this, if you're not able to build anything in at construction. Also bass traps in unused corners (wall ceiling junction is a corner too 😉 )

[Thorfun]

9 hours ago, saveasteading said:

Resilient is the right term, yes. 

found this system in the white book which i could emulate. might stick a 3rd layer of 12.5mm standard pb to the partition wall or a layer of MLV.

[Adrian Walker]

If you’re designing a music room make sure you don’t have any parallel walls. Standing waves will be a problem.